The invention relates to a device on a draw frame for textile slivers, having roller pairs arranged one after the other and a cleaning device, for example a cleaning lip, cleaning rod, or the like for one or more of the upper rollers.
In such form of draw frame, a loading device for each upper roller has at least two presser elements, for example pneumatic cylinders, each having a reciprocating component, for example a presser rod, piston rod, and the cleaning device is mounted on the loading device.
The draw frame is used to draft slivers, the slivers being clamped between two roller pairs with different rotational speeds. The roller pairs generally consist of a lower roller of steel and an upper roller having a resilient covering. The resilient covering has a tendency to wind up the silver. This is a very gradual process and begins with the picking-up of individual fibres. In order to avoid winding-up, attempts are made to remove these individual fibres from the upper roller and supply them to an extraction device by means of a cleaning bar (cleaning rod), which is usually round. The cleaning bar and the upper roller have to be arranged as far as possible axially parallel, so that linear contact is achieved. Otherwise the contact between the two components would be confined to a point and the cleaning action would thus be markedly reduced.
The guidance of the cleaning bar is generally effected by additional elements having guide grooves which have to be positioned relative to the upper roller. In a known device (DE 198 07 80) a holder for receiving a cleaning lip for the upper roller is provided on the pressure cylinder. When the loading device is pivoted away, the cleaning lip can also be pivoted away therewith. The holder has an elongate hole in which a journal of the cleaning lip is guided. A disadvantage is that when the upper roller bearing is relieved of load, that is to say when the piston rod has been lifted away from the upper roller bearing but the cylinder is still in position, the cleaning bar remains lying on the rubber covering of the upper roller. The rubber covering has an elevated operating temperature and is frequently sticky with honeydew, resulting in an undesirable linear load on the stationary rubber covering. A further problem is that the mounting arrangement of the journal of the cleaning lip in a vertical elongate hole on each side of the upper roller can give rise to a clamping moment. In practice, fibre material can become lodged in the elongate hole, namely between the journal and the inner walls of the elongate hole. As a result, the cleaning bar is unable to move away from the rubber covering.
It is an aim of the invention to provide a device of the kind described at the beginning which avoids or mitigates the mentioned disadvantages, which especially avoids impairment of the resilient covering of the upper roller when the piston rod is raised and which allows adaptable and stable guidance and mounting.